SPERC Background Document

May 2020

ESIG (European Solvents Industry Group)

Rue Belliard 40 b.15 B-1040 Brussels Belgium Tel. +32.2.436.94.88 esig@cefic.be www.esig.org

Specific Environmental Release Categories (SpERCs)

for the use of solvents and solvent-borne substances

in the industrial production and/or use of synthetic

rubbers, and blowing agents

Introduction

Organic solvents comprise a large group of volatile substances that belong to one of three broad

categories: hydrocarbon solvents, oxygenated solvents, and halogenated solvents. The commercial

production of these substances takes place in closed reactors located at large petrochemical facilities

that often operate adjacent to petroleum refineries supplying the raw feedstocks for their

manufacture.

Solvents are used in a variety of industrial and commercial applications that harness their ability to act

as extracting agents, solubilizers, cleansers or degreasers, and dispersing agents. Use of a solvent in a

particular application is dictated, in part, by its physical and chemical properties, which can vary over

a broad range. Solvents may also be used in combination when specific chemical characteristics are

needed for a particular process or product.

Solvent emissions can take place during their production, storage, transport, and use. Air, water, and

soil release are possible unless specific steps are taken to minimize or prevent the opportunity for

unintentional discharge. These measures include the creation of specific operational controls that

can be engineered into a product or process to limit environmental release and the potential for

exposure. Examples include the use of containment devices, temperature control, and automated

delivery systems. These control options are augmented by specific risk management measures

(RMMs) that lessen the likelihood of release to a particular environmental compartment. RMMs can

include any of a variety of pollution abatement technologies capable of capturing, neutralizing, or

destroying a vapour, gas, or aerosol.

The following guidance document provides a description of the logic and reasoning used to create

two Specific Environmental Release Categories (SpERCs). The air, water, and soil release factors

associated with these SpERCs and sub-SpERCs provide an alternative to the default release factors

associated with the environmental release categories (ERCs) promulgated by ECHA. The following

sections of this background document have been aligned with those of the SpERC Factsheet and

provide additional descriptive details on the genesis and informational resources used to generate

each SpERC.

SPERC BACKGROUND DOCUMENT 2

1. Title

The enclosed background information corresponds with the information provided in the following

two factsheets:

1. ESVOC SPERC 4.19a.v3 – Use in rubber production and processing

2. ESVOC SPERC 4.9.v2 – Use as blowing agents

Since these newly released SpERC factsheets include some corrections and or modifications, the

version number has been changed to reflect the updates.

2. Scope

The applicability domain for a particular SpERC includes an initial determination of the life cycle stage

(LCS) that best describes the industrial operation involved and the intended use of the substance

being evaluated. The relevant life cycle stages and their interrelationships are depicted in Figure 1

(ECHA, 2015). The two SpERCs highlighted in this guidance document are all associated with a single

life cycle stage: industrial end-use. This assignment is consistent with ECHA guidelines for

distinguishing solvent uses in industrial applications versus their wide-spread use in professional or

consumer applications.

Other use descriptors such as the sector of use (SU) and the chemical product category (PC) have

been assigned in accordance with the naming conventions outlined by ECHA (ECHA, 2015). These

have been summarized in Table 1 along with the use descriptions characterizing the two SpERCs. The

terminology used to describe the individual applications is consistent with the list of standard phrases

associated with the Generic Exposure Scenarios (GESs) that have been created to describe the

exposures associated with the industrial production and use of solvents (ESIG/ESVOC, 2017). Use of

standard phrases in these SpERC descriptions provides consistency and harmonization, and avoids

confusion among potential SpERC users.

Figure 1. ECHA identified life cycle stages and their interrelationship

SPERC BACKGROUND DOCUMENT 3

Table 1. SpERC background information

SpERC

Code Title

Life Cycle

Stage (LCS)

Sector of

Use (SU)

Chemical

Products

Category (PC)

Use

Description

ESVOC

SPERC

4.19a.v2

Use in rubber

production and

processing

Industrial

end-use

SU11

manufacture

rubber

products

PC0

other

Manufacture of tires and general

rubber articles, including

processing of raw (uncured)

rubber, handling and mixing of

rubber additives, vulcanising,

cooling and finishing.

ESVOC

SPERC

4.9.v2

Use as blowing

agents

Industrial

end-use

SU18

Manufacture

of furniture

PC32

polymer

preparations and

compounds

Use as a blowing agent for rigid

and flexible foams, including

material transfers, mixing and

injection, curing, cutting, storage

and packing

3. Operational conditions

The operating conditions for a particular industrial application define a set of procedures and use

conditions that limit the potential for environmental release. These system-related constraints are

typically optimized to minimize emissions and maximize product yield within a particular

manufacturing facility. Although the set of operating conditions applicable to a particular process

are highly specific, some general details can be used to characterize the various production

activities.

3.1. Conditions of use

Both SpERCs are applicable to indoor industrial operations that manufacture or use the products in a

controlled fashion that maximizes containment and minimizes opportunities for environmental

release. This includes the use of appropriate storage containers, transfer devices, and minimization

strategies for reducing product consumption. Open- and closed-loop batch reactors may also be

relevant for operations where a wide range of specialty products are handled. In most cases, these

operations do not use water as an extraction solvent, an adsorbent, or a reaction medium (OECD,

2011). The primary source of treatable wastewater results from the cleaning of drums, tanks, and

transfer equipment. These wastewaters are subsequently treated at either an industrial or a

municipal wastewater treatment (WWT) plant.

Evidence suggests, however, that municipal WWT plants are not widely used to process industrial

wastewaters. This is supported by several surveys of industrial wastewater treatment at European

facilities. The first involved a survey of WWT technologies at 81 European chemical facilities that

included both large integrated facilities and smaller dedicated stand-alone sites (EC, 2016). The

operations at these facilities included the production and formulation of a wide range of chemicals

and solvents for use in a wide range of downstream applications. The survey results indicated that a

majority (i.e. 89%) of the chemical facilities used a dedicated industrial wastewater treatment

facility; a much smaller percentage utilized a municipal treatment plant capable of handling both

industrial and domestic wastewater. The second survey of industrial operations in Germany found

that 4% of the wastewater generated was directed to municipal WWT plants (DECHEMA, 2017).

SPERC BACKGROUND DOCUMENT 4

Despite the limited reliance on municipal treatment facilities, their usage is conservatively assumed

to exist as a normal operating condition during the downstream use of solvents in industrial

operations.

Rigorous containment is not a necessary prerequisite for the application of these SpERCs to an

environmental exposure analysis. The European Chemical Agency has outlined the technical and

operational requirements necessary to demonstrate that a volatile organic compound (VOC) has

been rigorously contained. These include but are not limited to a variety of control measures that

minimize the release of a volatile solvent during processing or handling (ECHA, 2010). Strict

emission control is not a necessary prerequisite for the use of these SpERCs in the described

applications.

3.2. Waste handling and disposal

Every effort should be made to minimize the generation of waste solvents at every stage of the life

cycle. This includes the implementation of sensible waste minimization practices that stress the

importance of recycling and/or reuse. Under most circumstances, the residual waste generated

during the industrial use of a solvent-containing product is handled as a liquid or solid hazardous

waste (EEA, 2016). This designation applies to each of the SpERCs described herein and implies the

implementation of specific risk management measures to ensure proper storage, transport, and

disposal of the waste. These include a detailed written description of the physical form, industrial

source, and chemical composition of the waste; the use of continually monitored dedicated storage

bunkers or tanks for quarantining the waste; and the maintenance of up to date records

documenting the handling and disposal methods (EA, 2004). The residual hazardous waste may be

disposed of through thermal incineration using any of several high efficiency equipment designs

including rotary kilns (EC, 2017).

4. Obligatory risk management measures onsite

Application of the described SpERCs is not dependent on the implementation of obligatory RMMs to

control atmospheric release during production or processing. It is assumed, however, that all

applicable industrial operations include intensive and detailed housekeeping practices that help

minimize environmental release. In addition, biological wastewater treatment is an obligatory risk

management measure that ensures the biodegradation of any water-soluble volatile substance prior

to discharge in a local waterway. It is also supposed that all immiscible liquids have been removed

from the wastewater influent using an acceptable oil-water separator or dissolved gas flotation

device. Finally, onsite or offsite hazardous waste destruction of any unrecovered solvents is a

necessary waste management practice (ECHA, 2012).

These required measures can be supplemented with any of several optional control devices that can

further reduce environmental emissions. When implemented, the effectiveness of these measures

may be used to reduce the release factors associated with the applicable sub-SpERC.

SPERC BACKGROUND DOCUMENT 5

4.1. Optional risk management measures limiting release to air

The following optional RMMs may be applicable to some or all of the SpERCs highlighted in this

guidance document. If relevant, the stated air release factors may be adjusted downward to

account for the additional reductions in environmental emission. Seven treatment technologies

have been cited in Table 2 along with the range of measured removal efficiencies, the assigned

nominal removal efficiency for use when adjusting the assigned air emission factor, and the SpERCs

where the technology may be applicable.

The treatment technologies include wet scrubbers, thermal oxidation, vapour adsorption,

membrane separation, biofiltration, cold oxidation, and air filtration (EC, 2016, Schenk, et al., 2009).

The removal efficiency of wet scrubbers for VOCs can vary depending on the plant configuration,

equipment operating conditions, and the type of VOC. The range of removal efficiencies cited in

Table 2 reflect the variability that has been observed in two separate determinations. Two of these

determinations found a removal efficiency of 70% or greater, whereas a third reported a range of 50

- 95%. The latter measurements included the use of a fibrous bed scrubber which is best suited for

use with particulates. Taking these facts into consideration, a conservative default value of 70% was

judged to be representative of the removal efficiency of wet scrubbers for solvent volatiles.

Table 2. Treatment technologies and removal efficiencies for reducing the air emission

factors for VOCs

Air

abatement

technology

Reported

abatement

efficiency

range (%)

Assigned

abatement

efficiency

(%)

Applicability to individual SpERCs

ESVOC SPERC

4.19a.v3

ESVOC SPERC

4.9.v2

wet scrubbers 50 - 99 70 X Z

thermal

oxidation 95 - 99.9 95 X X

solid

adsorbent 80 - 95 80 X Z

membrane

separation <99 80 Z Z

biofiltration 75 - 95 75 Z Z

cold

oxidation 80 - >99.9 80 Z Z

air

filtration 70 - 99 70 X Z

X – abatement technology broadly applicable

Z – abatement technology may be applicable

SPERC BACKGROUND DOCUMENT 6

The abatement efficiency of thermal oxidizers was found to range from 95 - 99% in one study and 98

- 99.9% in another. A conservative default value of 95% was established at the low end of the

distribution to ensure that an adequate margin of safety had been incorporated into any emission

factor adjustment. The use of solid adsorbents such as granular activated carbon, zeolite, or

macroporous polymers offered capture efficiencies ranging from 80 - 99% in three separate studies.

A nominal default value of 80% was determined to provide adequate assurance that the removal

efficiency for this technology was not overestimated. Membrane separation techniques allow for

the selective recovery of a volatile substance and can yield a range of efficiencies up to 99%

depending on flow rates, properties of the substance, and membrane type. A nominal removal

efficiency of 80% was assigned to this technology to ensure that an adequate margin of protection is

included in any emission factor adjustments.

Removal efficiencies ranging from 75 - 95% have been observed when biofilters are used as an

emission abatement technology for volatile substances. The variance is due in part to the wide

range of biological materials that can be used to construct the filtration bed (e.g. peat, compost, tree

bark, and softwoods). To account for the variability and ensure adequate caution, a nominal

removal efficiency of 75% should be applied when this technology is in use. Cold oxidation methods

for emission abatement include systems capable of ionizing and oxidizing a vapour through the

application of a strong electric current. Differences in equipment design and operational conditions

can affect the removal efficiencies observed using this approach. The nominal removal efficiency of

a volatile substance by cold oxidation has been set at the lower end of the observed range of 80 -

>99%. Higher removal efficiencies may be applied when any of these technologies are used in

combination within a vapor recovery unit. Air filtration techniques such as wet dust scrubbing may

be used to remove soluble particulate matter, aerosols, and mist from an airstream. The removal

efficiencies attainable with these methods varies depending the type of scrubber being used, with

reductions of 70 - 99% observed with a fibrous packing scrubber using glass, plastic, or steel packing

material.

The preceding list of air treatment technologies is not exhaustive; others may exist that are capable

of capturing volatiles and ameliorating the air emission profile. These include technologies such as

cryo-condensation, bio-trickle filtration, and bio-scrubbing. If they apply, the abatement efficiencies

for these emission control devices can be retrieved from either of several different literature sources

(EC, 2016, Schenk, et al., 2009).Optional risk management measures limiting release to water

The SPERC release factors assume that there is no undissolved material in the wastewater stream

being biologically degraded. If this is not the case then the immiscible liquids need to be removed

using either of several separation techniques. These include the use of oil-water separators or

dissolved gas flotation devices. Oil-water separators employing a skimming device for oil removal

have been shown to operate with an abatement efficiency of 80 - 95% depending on the equipment

design, the amount of immiscible material in the wastewater, and the physical characteristics of the

recoverable material (EC, 2016). Most equipment designs incorporate i) parallel plate or corrugated

plate interceptors or ii) the American Petroleum Institute (API) mechanical separator.

SPERC BACKGROUND DOCUMENT 7

Dissolved gas flotation devices use pressurized gas treatment to generate small gas bubbles that

capture any suspended oil. The removal efficiency using this treatment technology can vary from 50

- 90% depending the specific characteristics of the wastewater stream (Galil and Wolf, 2001).

Flocculants may be added to the wastewater stream to improve coagulation and entrapment of the

emulsified oil.

4.3. Optional risk management measures limiting release to soil

The emission factors are only applicable to facilities and operations were there is no application of

WTP sludge to agricultural soil or arable land (ECHA, 2016). It also understood that good

housekeeping and maintenance procedures are in place to minimize the potential for soil release.

Aside from these requirements, there are no discretionary risk management measures that may be

instituted to minimize the release of volatile substances to soil (CEFIC, 2007).

5. Exposure assessment input

The exposure scenarios used to evaluate the potential risk from the environmental release of a

substance are highly dependent on the identification of certain key parameters that allow the air,

water, and soil concentrations to be predicted. Factors such as the use rate, emission duration, and

environmental release magnitude need to be quantified and substantiated in a manner that provides

credence to final risk determination. This section of the background document describes the

approach, reasoning, and information resources used to establish a reasonably conservative value

for these key parameters.

5.1. Substance use rate

The two SpERCs identified in this guidance document have slightly dissimilar maximum estimated

usage rates that reflect differences in the handling capacities at different industrial sites (see Table

3). The maximum site tonnages have been established using expert sector knowledge along with

published information that provides representative nameplate capacities at typical site operations.

The stated values provide a realistic worst-case estimate of the usage per day and may be modified

if i) more realistic data is available; ii) the use amount needs to be limited to manage the

environmental risk; and iii) the number of emission days is less than the cited value. The local or

regional fractional use tonnages are generally adjusted for the wide dispersive uses that accompany

professional and consumer applications, so there has not been any modification for the industrial

applications described in these two SpERCs.

SPERC BACKGROUND DOCUMENT 8

Table 3. Maximum estimated rates of usage and the fractional tonnages used at the local

and regional level

Tonnage

SpERC title

ESVOC SPERC 4.19a.v3 ESVOC SPERC 4.9.v2

Local use rate

(kg/day) 100,000 50,000

Emission days 300 300

Fractional local

EU tonnage 100% 100%

Fractional

regional EU

tonnage

100% 100%

Rationale published citation tanker truck

shipments

The estimated local use rate at sites manufacturing blowing agents was based on professional

judgement and take into consideration the number of tanker trucks that are off-loaded at a

representative facility per day. These tankers are assumed to operate in accordance with EU

Directive 96/53/EC governing the maximum authorized weights and dimensions of road trailers in

Europe (EU, 1996). In agreement with the legislation, the payload capacity of the transport vehicles

is presumed to be 25 metric tons (Znidaric, 2015). The number of off-loaded tanker trucks

processed at a site was conservatively estimated to be 2 per day for use as a blowing agent. The

equation used to calculate the use rates is as follows:

𝑈𝑠𝑒 𝑟𝑎𝑡𝑒 (𝑘𝑔

𝑑𝑎𝑦) = 𝑡𝑎𝑛𝑘𝑒𝑟 𝑝𝑎𝑦𝑙𝑜𝑎𝑑 (𝑡𝑜𝑛𝑛𝑒𝑠) × 𝑙𝑜𝑎𝑑𝑖𝑛𝑔 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦 (

𝑡𝑎𝑛𝑘𝑒𝑟𝑠

𝑑𝑎𝑦) × 1000 (

𝑘𝑔

𝑡𝑜𝑛𝑛𝑒) ( 1 )

The local use rate for the rubber manufacturing SpERC was estimated using published information

on production volume of synthetic rubbers in the European Union (Rubber-Economist, 2009). An

evaluation of synthetic rubber production capacity in 12 EU countries reported a 2008 volume of 2.5

million tonnes. This volume was projected to decline by about 17% over the next three years. This

2008 value equates to 208,000 tonnes per region or 20,800 tons per manufacturing site, assuming

that there are at least 10 manufacturing operations per region. Based on this analysis, the use rate

per site was conservatively assumed to be no greater than 300,000 tonnes/year or 100,000 kg/day

for a 300-day production cycle. The equation used to calculate the overall use rate is as follows:

𝑈𝑠𝑒 𝑟𝑎𝑡𝑒 (𝑘𝑔

𝑑𝑎𝑦) =

𝑝𝑙𝑎𝑛𝑡 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦 (𝑡𝑜𝑛𝑛𝑒𝑠

𝑦𝑒𝑎𝑟) × 1000 (

𝑘𝑔

𝑡𝑜𝑛𝑛𝑒)

𝑜𝑝𝑒𝑟𝑎𝑡𝑖𝑛𝑔 𝑝𝑒𝑟𝑖𝑜𝑑 (𝑑𝑎𝑦𝑠

𝑦𝑒𝑎𝑟)

( 1 )

The preceding determinations provide a conservative estimate of the of the use rate that can be

expected at production and use facilities in Europe.

SPERC BACKGROUND DOCUMENT 9

5.2. Days emitting

The number of emission days is the same for each of the SpERCs described in this guidance

document (see Table 3). The value of 300 days/year is the default value for substances used in

industrial applications in an amount greater than 5,000 tonnes/year (ECHA, 2016). The tonnage cut-

off limits cited above represent the maximum use amount at a single site.

5.3. Release factors

The magnitude of an environmental emission following the production or use of a volatile solvent

may be impacted by its water solubility and volatility (OECD, 2011). Since these properties can vary

over a wide range for the bulk commodity solvents found in commerce, a single emission factor does

not adequately portray the release of all the chemicals in this class. This has prompted the

identification of individual emission factors that reflect the differences in the physical and chemical

properties of a volatile substance. Numerical classification allows solvents with high water solubility

or volatility to be distinguished from those with a low to intermediate values. Using this approach, a

single vapor pressure category was used along five water solubility categories to define five sub-

SpERCs for each identified use. This yielded a more precise scheme for assigning a release factor to

a volatile solvent with particular water solubility characteristics.

a) Release factor to air

A failure to locate suitable information across a range of vapor pressure categories necessitated a

pragmatic assignment of air release factors. When reliable information was unavailable for the

solvents used in a particular industrial application, a worst-case default estimate was applied.

Otherwise, published air release factors were applied once the information was suitably vetted.

Table 5 provides a listing of the emission factors and their associated literature sources for each of

the two SpERCs being considered.

Table 5. SpERC release factors for air

Assignments

SpERC title

rubber

processing

blowing

agent use

Air release factor

(%) 1.0 98

Source (OECD, 2004) (ECHA, 2016)

1. Use in rubber production and processing

The air release factor for synthetic rubber production has been taken from an analysis performed in

the OECD Emission Scenario Document (ESD) for the rubber industry (OECD, 2004). The value of

1.0% is applicable to polymer industry processing aids with a vapour pressure greater than 100 Pa

and a boiling point less than 300 °C. The OECD assigned air emission factor was associated with the

Appendix I A-Table value assigned to substances used in the polymer industry (EC, 2003).

SPERC BACKGROUND DOCUMENT 10

2. Use as blowing agents

The ERC 4 default value of 98% has been adopted since factual information describing the actual air

emission value is unavailable (ECHA, 2016). The listed default value has been attributed to the use

of non-reactive processing aids at an industrial site (no inclusion into or onto article). Processing

aids include the use of solvents in continuous or batch processes using dedicated or multi-purpose

equipment that is either automatically or manually controlled. The genesis of this value reportedly

stems from an examination of the release factors posted in the A-Tables of Appendix 1 in the

Technical Guidance Document (TGD) on Risk Assessment PART II (EC, 2003).

The air emission factors shown in Table 5 have not been adjusted for the potential use of an

emission abatement device such as those described in section 4.1. Using fractional values, the

adjustment is easily calculated using the following formula:

𝐴𝑑𝑗𝑢𝑠𝑡𝑒𝑑 𝑟𝑒𝑙𝑒𝑎𝑠𝑒 𝑓𝑎𝑐𝑡𝑜𝑟 = 𝑢𝑛𝑎𝑑𝑗𝑢𝑠𝑡𝑒𝑑 𝑟𝑒𝑙𝑒𝑎𝑠𝑒 𝑓𝑎𝑐𝑡𝑜𝑟 × (1 − 𝑎𝑏𝑎𝑡𝑒𝑚𝑒𝑛𝑡 𝑟𝑒𝑚𝑜𝑣𝑎𝑙 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦) ( 3 )

The use of an adjusted air emission factor in a SpERC application must be fully documented and

explained in the Chemical Safety Report.

b) Release factor to water

The fractional release of a volatile substance into the wastewater stream can be calculated as the

ratio of the released mass to the overall production mass. The mass of a volatile solvent released to

wastewater is limited by its water solubility, which provides a worst-case estimate of the mass

concentration that can exist in the wastewater stream slated for treatment in a WWTP. To calculate

a water release fraction from the water solubility values, the volume of wastewater produced per

unit mass of final product (i.e., m3 wastewater/ tonne produced) needs to be known. Using this

information, the water release factor can be calculated using the following formula:

𝑅𝑒𝑙𝑒𝑎𝑠𝑒 𝑓𝑎𝑐𝑡𝑜𝑟 (%) = (𝑤𝑎𝑠𝑡𝑒𝑤𝑎𝑡𝑒𝑟 𝑣𝑜𝑙𝑢𝑚𝑒 (

𝑚3

𝑡𝑜𝑛𝑛𝑒) × 𝑤𝑎𝑡𝑒𝑟 𝑠𝑜𝑙𝑢𝑏𝑖𝑙𝑖𝑡𝑦 (

𝑚𝑔

𝐿) × 1000 (

𝐿

𝑚3)

1.0×109 (𝑚𝑔

𝑡𝑜𝑛𝑛𝑒)

) × 100 ( 2 )

This allows the water release factors to be calculated for the five water solubility categories. When

the water solubility category was described as a numerical range, the geometric mean for the upper

and lower limits of the range were used to determine a unique solubility value for that category. For

instance, a value of 3.2 mg/L was used to describe the water solubilities ranging from 1 - 10 mg/L.

Several sources of information were used to identify a representative wastewater generation

volume normalized for production capacity. These sources are individually highlighted in Table 6

along with the reported and functionally applied wastewater generation volumes.

1. Use in rubber production and processing

The production and processing of synthetic and natural rubbers both rely on the use of solvents for

extraction and solvation. A large percentage of these solvents are recovered and reused as an

integral part of the production process, but some is released. Unlike synthetic rubber which is

polymeric, natural rubber is an elastomer made from the latex found in certain types of vegetation.

SPERC BACKGROUND DOCUMENT 11

One type of natural rubber that is being increasingly used in the production of automobile tires uses

the sap from the guayule plant as a latex source. A recent life cycle assessment (LCA) reported that

16 kg of solvent are used for latex extraction for every kg of guayule rubber that is produced using a

upgraded batch processing method (Azarabadi, et al., 2017). In a separate LCA study, focusing on

guayule rubber production by the same method and at the same facility, 68.41 kg of water were

reportedly used to produce a kg of natural rubber (Eranki and Landis, 2019). Assuming a solvent

density of 1000 kg/m3, the ratio of these two values yields a wastewater generation volume of 4.25

m3/tonne of solvent used. To ensure an adequate safety margin, this value has been rounded

upward to 10 m3/tonne (see Table 6), which is the value used to calculate the water release factors

for the solvents used in rubber production and processing.

2. Use as blowing agents

Blowing agents encompass a wide array of solid, liquid, and gaseous chemicals including high vapor

pressure hydrocarbons such as n-pentane, cyclopentane, and iso-butane (Singh, 2002). Blowing

agents function as reactive additives to plastics and polymers that cause the formation of closed

cellular structures within the resulting foam product. A life cycle assessment examined the

production of an expanded polystyrene resin that utilized n-pentane as the blowing agent during

final foam formation (EPS Indusrry Alliance, 2016). A survey of three expanded polystyrene resin

manufacturers in Canada, Mexico, and the US yielded information on pentane usage and water

consumption. The results showed an average water consumption of 0.829 m3 per 1000 kg of resin

and an average pentane usage of 0.0683 tonne per 1000 kg of resin. The quotient for these two

numbers yields a wastewater generation volume of 12.1 m3/tonne of blowing agent consumed.

Since the production techniques used to manufacture expanded polystyrene resin are highly

representative of the processes used to manufacture other foam polymers, the reported waste

water generation volume required no further adjustment (see Table 6).

Table 6. Wastewater generation volumes associated each industrial use SpERC

Assignments

SpERC title

rubber

processing

blowing

agent use

Reported

WWTP volume

(m3/tonne)

4.25 12.1

Functional WWTP

volume (m3/tonne) 10 12

Source (Azarabadi, et al., 2017,

Eranki and Landis, 2019) (EPS Indusrry Alliance, 2016)

The functional WWTP were used to calculate the water release factors listed in Table 7 for the two

SpERCs highlighted in this guidance document. The values provide a conservative, data-drive,

approximation of aqueous solvent release as a function of its water solubility.

SPERC BACKGROUND DOCUMENT 12

As noted above, the water release factors were calculated at the midpoint of the water solubility

range. If specific knowledge is available on the water solubility of the solvents being used in a

particular application, the release factors may be adjusted to account for the difference between the

actual and nominal water solubility values.

Table 7. SpERC water release factors for each water solubility category

Water solubility

(mg/L)

SpERC water release factor (%)

Rubber processing Blowing agent

<1 0.001 0.001

1-10 0.003 0.004

10-100 0.03 0.04

100-1000 0.3 0.4

>1000 1.0 1.2

c) Release Factor - soil

The SpERC-related soil release factors have been compiled from several different sources. As shown

in Table 8, a value of zero or 0.01 has been assigned using ECHA-reported default assessments or

professional judgement together with available sector knowledge. The soil release factor for the

rubber processing SpERCs is equivalent to the default values associated with the corresponding ERC

(ECHA, 2016).

The soil release values have all been conservatively estimated with the understanding that some

release to soil may occur during equipment upsets. These include the spillages that may accompany

the transfer or delivery of materials and the development of leaks in pumps, pipes, reactors, and

storage tanks. In addition, the supplied soil release factor takes into consideration the wet and dry

soil deposition that may accompany the airborne release of a volatile substance. Soil releases from

these situations are not expected to be a common occurrence because a majority of the operations

covered by these SpERCs take place indoors.

Table 8. SpERC release factors for soil

Assignments SpERC title

Rubber processing Blowing agent

ERC 4 4

Soil release

factor (%) 0.01 0

Source (ECHA, 2016) professional judgement

SPERC BACKGROUND DOCUMENT 13

c) Release Factor – waste

A thorough and detailed analysis accompanied the assignment of waste release factors for the two

SpERCs outlined in this background document. Although a substantial amount of information is

available documenting the total amount of different waste types produced annually by solvent

users, these data are often in a form that prevents the determination of a normalized release

fraction as a function of the production capacity. Life cycle studies can provide useful statistics on

waste generation in different industrial use sectors; however, these studies need to be individually

examined to determine their relevance to a particular SpERC code.

In this context, waste refers to solvent-containing substances and materials that have no further use

and need to be disposed of in a conscientious manner (Inglezakis and Zorpas, 2011). The chemical

industry is capable of generating a wide range of hazardous wastes ranging from spent catalysts to a

variety of sludges, waste oils, unreacted residues (UNEP, 2014). Waste volumes are dramatically

affected by recovery and reuse practices and marketing opportunities that take advantage of any

residual value to downstream industries (i.e. industrial symbiosis) (EC, 2015). These practices have

allowed the petrochemical industry to conserve resources, optimize operations, and implement new

sustainability initiatives that promote alternative applications for these residues and by-products

(EEA, 2016).

The waste release factors cited in Table 9 have all been derived from published life cycle

assessments (LCAs) that inventory the emissions and wastes generated during the different stages of

a product’s service life. These values may be used in the absence of detailed information for a

particular industrial operation. These generic values may be supplanted if the actual hazardous

waste generation factor is known for the industrial operation under consideration. To guarantee

that an adequate margin of protection was built into the determination, an adjustment factor of 10

has occasionally been applied when a reported value was judged to be unrepresentative for the

entire range of potential use conditions within a particular industrial sector.

The waste fraction associated with the industrial processing of synthetic rubber products has been

inferred from an LCA of plastic parts manufacturing using injection moulding machines (Öncel, et al.,

2017). The generation of hazardous solvent waste composed of halogenated solvents, washing

liquids, and mother liquors was found to range as high as 4.0%. Since the production of synthetic

rubber products such as seals and gaskets may involve an extrusion step before vulcanization, the

waste factor for plastic parts manufacturing provided reasonably robust surrogate information for

the rubber processing SpERC. An LCA for the commercial production of flexible polyurethane foams

using an unstated blowing agent provided an estimate of the waste associated with this operation

(Plastics Europe, 2005). The amount of incinerated solid waste associated with foam production was

determined to be 2.0%. An uncertainty factor was not been applied to the waste factors for rubber

processing and blowing agent SpERCs because the cited waste factors include substantial quantities

of hazardous waste that has not come into contact with a volatile solvent.

SPERC BACKGROUND DOCUMENT 14

Table 9. SpERC waste release factors and their literature source

Assignments

SpERC title

rubber

processing

blowing

agent

Release factor

(%) 4.0 2.0

Source (Öncel, et al., 2017) (Plastics Europe, 2005)

6. Wastewater Scaling Principles

Scaling provides a means for downstream users (DUs) to confirm whether their combination of OCs

and RMMs yield use conditions that are in overall agreement with those specified in a SpERC (ECHA,

2014). This consistency check may be accomplished by multiple methods aimed at ensuring that the

environmental concentrations resulting from the combination of conditions present at a DU site are

less than or equivalent to the levels associated with a SpERC. Scaling principles recognize that a

linear relationship exists between the predicted environmental concentration and some, but not all,

use determinants (CEFIC, 2010). Factors such as the use amount, the application of emission

reduction technologies, wastewater treatment plant capacity, and effluent dilution are all scalable

parameters that can be taken into consideration when applying SpERC emission factors to a separate

set of circumstances.

The underlying mathematical relation that forms the basis for SpERC scaling is as follows:

𝑃𝐸𝐶𝑠𝑖𝑡𝑒 = 𝑃𝐸𝐶𝑆𝑃𝐸𝑅𝐶 ×𝑀𝑠𝑖𝑡𝑒

𝑀𝑆𝑃𝐸𝑅𝐶×

𝑅𝐸𝑡𝑜𝑡𝑎𝑙,𝑠𝑖𝑡𝑒

𝑅𝐸𝑡𝑜𝑡𝑎𝑙,𝑆𝑃𝐸𝑅𝐶×

𝐺𝑒𝑓𝑓𝑙𝑢𝑒𝑛𝑡,𝑠𝑖𝑡𝑒

𝐺𝑒𝑓𝑓𝑙𝑢𝑒𝑛𝑡,𝑆𝑃𝐸𝑅𝐶×

𝑞𝑠𝑖𝑡𝑒

𝑞𝑆𝑃𝐸𝑅𝐶×

𝑇𝑒𝑚𝑖𝑠𝑠𝑖𝑜𝑛,𝑠𝑖𝑡𝑒

𝑇𝑒𝑚𝑖𝑠𝑠𝑖𝑜𝑛,𝑆𝑃𝐸𝑅𝐶 ( 3 )

Where:

PECsite – predicted environmental concentration from use at a DU site (g/L)

PECSPERC – predicted environmental concentration from the use of a SpERC (g/L)

Msite – local use amount at a DU site (kg/day)

MSPERC – worst-case estimate of the local use amount associated with a SpERC (kg/day)

Temission,site – number of emission days at a DU site (days)

Temission,SPERC – number of emission days cited for a SpERC (days)

REtotal,site – total removal efficiency associated with the application of optional RMMs at a

DU site (fraction)

REtotal,SPERC – total removal efficiency associated with the application of mandatory RMMs for

a SpERC (fraction)

Geffluent,site – DU sewage treatment plant flow rate (m3/day)

Geffluent,SPERC – SpERC cited sewage treatment plant flow rate (m3/day)

qsite – receiving water dilution factor applicable to the DU site (unitless)

qSPERC – receiving water dilution factor applicable to a SpERC (unitless)

SPERC BACKGROUND DOCUMENT 15

Equation 5 shows that a proportionality relationship exists between the use conditions associated

with a SPERC and the use conditions that actually exist at a DU site (ECHA, 2008). This relationship

forms the basis for ensuring conformity when the wastewater operating conditions differ at a DU

site. The scalable parameters described in equation 5 are not equally applicable to every type of

environmental risk. As depicted in equations 6-8, the number of scalable parameters increases as

the environmental risk of concern become more removed from the wastewater treatment site

(CEFIC, 2012). Consequently, the environmental risk to (1) STP microorganisms, (2) organisms

residing in the water column and sediment (i.e., freshwater and marine plants and animals), and (3)

apical freshwater and marine predators in the aquatic food chain (i.e., secondary poisoning) utilize

slightly different scaling equations. Environmental risk is adequately controlled at each trophic level

if the following relationships are maintained and the calculations from the SpERC side of the

equations are greater than or equal to the results obtained using the site-specific parameters.

Scaling for environmental risk to wastewater treatment plant microorganisms:

𝑀𝑆𝑃𝐸𝑅𝐶 × (1−𝑅𝐸𝑡𝑜𝑡𝑎𝑙,𝑆𝑃𝐸𝑅𝐶)

𝐺𝑒𝑓𝑓𝑙𝑢𝑒𝑛𝑡,𝑆𝑃𝐸𝑅𝐶≥

𝑀𝑠𝑖𝑡𝑒 × (1−𝑅𝐸𝑡𝑜𝑡𝑎𝑙,𝑠𝑖𝑡𝑒)

𝐺𝑒𝑓𝑓𝑙𝑢𝑒𝑛𝑡,𝑠𝑖𝑡𝑒 ( 4 )

Scaling for environmental risk to freshwater/freshwater sediments, marine water/marine water

sediments:

𝑀𝑆𝑃𝐸𝑅𝐶 × (1−𝑅𝐸𝑡𝑜𝑡𝑎𝑙,𝑆𝑃𝐸𝑅𝐶)

𝐺𝑒𝑓𝑓𝑙𝑢𝑒𝑛𝑡,𝑆𝑃𝐸𝑅𝐶 × 𝑞𝑆𝑃𝐸𝑅𝐶 ≥

𝑀𝑠𝑖𝑡𝑒 × (1−𝑅𝐸𝑡𝑜𝑡𝑎𝑙,𝑠𝑖𝑡𝑒)

𝐺𝑒𝑓𝑓𝑙𝑢𝑒𝑛𝑡,𝑠𝑖𝑡𝑒 × 𝑞𝑠𝑖𝑡𝑒 ( 5 )

Scaling for environmental risk to higher members of the food chain (freshwater fish/marine top

predator) or indirect exposure to humans by the oral route:

𝑀𝑆𝑃𝐸𝑅𝐶 × 𝑇𝑒𝑚𝑖𝑠𝑠𝑖𝑜𝑛,𝑆𝑃𝐸𝑅𝐶 × (1−𝑅𝐸𝑡𝑜𝑡𝑎𝑙,𝑆𝑃𝐸𝑅𝐶)

𝐺𝑒𝑓𝑓𝑙𝑢𝑒𝑛𝑡,𝑆𝑃𝐸𝑅𝐶 × 𝑞𝑆𝑃𝐸𝑅𝐶≥

𝑀𝑠𝑖𝑡𝑒 × 𝑇𝑒𝑚𝑖𝑠𝑠𝑖𝑜𝑛,𝑠𝑖𝑡𝑒 × (1−𝑅𝐸𝑡𝑜𝑡𝑎𝑙,𝑠𝑖𝑡𝑒)

𝐺𝑒𝑓𝑓𝑙𝑢𝑒𝑛𝑡,𝑠𝑖𝑡𝑒 × 𝑞𝑠𝑖𝑡𝑒 ( 6 )

The total removal efficiency (REtotal) is equal to the product of the removal efficiencies attained using

onsite and offsite abatement technologies and is calculated as shown in equation 9.

𝑅𝐸𝑡𝑜𝑡𝑎𝑙,𝑠𝑖𝑡𝑒 = 1 − [1 − (𝑅𝐸𝑜𝑛𝑠𝑖𝑡𝑒,𝑠𝑖𝑡𝑒) × (1 − 𝑅𝐸𝑜𝑓𝑓𝑠𝑖𝑡𝑒,𝑠𝑖𝑡𝑒)] ( 7 )

In some cases, an easier and more direct scaling approach may be used that compares individual

operational parameters on an item by item basis. This approach allows the individual comparison of

local use amounts (Msafe), emission days per year (Temission,site), effluent flow rate (Geffluent,site), receiving

water dilution (qsite), and total abatement removal efficiency (REtotal,site). Adequate control of

environmental risk exists if Msafe Msite and the remaining operational conditions comply with the

following conditions:

Msafe Msite

Temission,SPERC Temission,site

SPERC BACKGROUND DOCUMENT 16

REtotal,site REtotal,SPERC

Geffluent,site Geffluent,SPERC

qsite qSPERC

Msafe (kg/day) is equivalent to the local use amount that yields a risk characterization ratio (RCR) of 1.

As such, it represents the maximum tonnage that can be used in conjunction with a prescribed set of

operational conditions.

The water release factors provided in this background document represent an additional set of

potentially scalable parameters; however, refining the specified values requires detailed justification

that goes well beyond the scope of this communication. For this reason, water release factor

adjustments are not offered as a feasible alternative when opting for a SPERC-based assessment.

DU users need to independently derive and rationalize any release factor modifications that are

ultimately used to support their chemical safety assessment.

7. References

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SPERC BACKGROUND DOCUMENT 17

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SPERC BACKGROUND DOCUMENT 18

EU, 1996. Council Directive 96/53/EC of 25 July 1996 laying down for certain road vehicles circulating within the Community the maximum authorized dimensions in national and international traffic and the maximum authorized weights in international traffic. Official Journal of the European Union. Luxembourg. https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:31996L0053&from=en. Galil, N.I., Wolf, D., 2001. Removal of hydrocarbons from petrochemical wastewater by dissolved air flotation. Water Science and Technology 43, 107-113. doi: 10.2166/wst.2001.0476. Inglezakis, J.V., Zorpas, A., 2011. Industrial hazardous waste in the framework of EU and international legislation. Management of Environmental Quality: An International Journal 22, 566-580. doi: 10.1108/14777831111159707. OECD, 2004. Emission Scenario Documents on Additives in Rubber Industry. No. 6, Organisation for Economic Co-operation and Development. Paris, France. http://www.oecd.org/officialdocuments/publicdisplaydocumentpdf/?cote=env/jm/mono(2004)11&doclanguage=en. OECD, 2011. Emission Scenario Document on the Chemical Industry. No. 30, Organisation for Economic Co-operation and Development. Paris, France. http://www.oecd.org/env/ehs/risk-assessment/48774702.pdf. Öncel, M.S., Bektaş, N., Bayar, S., Engin, G., Çalışkan, Y., Salar, L., Yetiş, Ü., 2017. Hazardous wastes and waste generation factors for plastic products manufacturing industries in Turkey. Sustainable Environment Research 27, 188-194. doi: 10.1016/j.serj.2017.03.006. Plastics Europe, 2005. Eco-profiles of the European Plastics Industry: Polyurethane Flexible Foam. Association of Plastics Manufacturers. Brussels, Belgium. https://isopa.org/media/1091/flexible-foam-lci.pdf. Rubber-Economist, 2009. The Rubber Economist Quarterly Report - 3rd Quarter 2009 Edition. Rubber Economist, Ltd. Surrey, United Kingdom. http://www.therubbereconomist.com/Quarterly_Report.html. Schenk, E., Mieog, J., Evers, D., 2009. Fact sheets on air emission abatement techniques Royal Haskoning DHV. Amersfoort, The Netherlands. Singh, S.N., 2002. Blowing agents for polyurethane foams. Rapra Review Reports 12, 78-91. UNEP, 2014. Methodological Guide for the development of inventories of hazardous wastes and other wastes under the Basel Convention. United Nations Environment Programme. Chatelaine, Switzerland. http://www.basel.int/Implementation/Publications/GuidanceManuals/tabid/2364/Default.aspx. Znidaric, A., 2015. Heavy-Duty Vehicle Weight Restrictions in the EU: Enforcement and Compliance Technologies. Slovenian National Building and Civil Engineering Institute. Ljubljana, Slovenia. https://www.acea.be/uploads/publications/SAG_23_Heavy-Duty_Vehicle_Weight_Restrictions_in_the_EU.pdf.